Thermionic emission source



Sept. 2, 1958 M. w. ECHO THERMIONIC EMISSION SOURCE Filed Aug. 19, 1955 INVENTOR.

M.W. ECHO 7 HWXM ATTORNEY Fatented Sept. 2, llfififd i cc spacers, one of which is shown at 12. This filament holder is detachably secured to an electrode, for example, an anode block 13 in the manner hereinafter 2,359,633 explained in detail, the block 13 being suitably secured m H m r to a base ring 14 which is connected to the end of a n RMIQNKC EMHSBION SDURCE metal tube, not shown, which is a part of the spectrom- .i ten Maurice W. Echo, Idaho Falls, ldaho, assignor to Philiips eter vacuum lock and contains the electrical leads for Petroleum tlompany, a corporation of Delaware h tub la A filament 15 is carried by slotted end portions lea,

AP p M31013 Augus'i 1955 Sena! 529550 17a of a pair of triangular filament supports 16 and i7 6 Claims. (Cl. 250-419) which are secured to the respective filament holder sections 10 and 11. The filament can be a strip of tantalum ribbon 0.001" by 0.030". One end of this ribbon extends through an opening 18 in the holder section 11 and This invention relates to a thermionic emission source. is secured in position within this opening by a bolt 19 in another aspect, it relates to a readily replaceable filaextending through a tapped opening 20 in the section ll. ment for a mass spectrometer. The other end of the ribbon extends through an opening Heretofore, in making analyses with mass spectrom- 21 in the filament holder section 10 and is held in posieters, the filament has been secured, as by spot weldtion by a bolt, not shown, similar to the bolt 19, which ing, to suitable glass-to-metal seals. Inasmuch as it is 20 extends throughatapped opening in the section iii. Thus, desired to deposit samples to be analyzed on the filament to install or remove the filament, it is only necessary to in many instances, it is desirable that the filament be loosen the bolts and withdraw or insert the ends of the readily removable and replaceable. Where the previous ribbons from or in the openings 18 and 21. The bolts, constructions have been utilized, quite marked variations in their clamped position, securely hold the filament in in filament position have been noted, and jig setting of the position as determined by the edges of the slotted end filament is required before each use. portions 16a and 17a.

In accordance with this invention, the filament or When the filament holder is clamped into position, emission source is carried by a pair of slotted members as hereinafter described, the filament protrudes into a protruding from a metal block having two sections inslot 22 formed in the anode block 13 and is positioned sulated from each other. This block can be readily adjacent a pair of focus plates 23 and 24 which are sesnapped into place on an electrode assembly and coopercured to the anode block by a bolt 25 and spaced thereates with aspn'ng pressed spacer ball assembly so that it is from by sapphire ball spacers 26 fitting into suitable readily removable. In its assembled position, the source openings 27 in the focus plates. is accurately positioned in an immovable manner, and The filament holder assembly can be readily clamped electrical connections are made to the two filament terinto position upon the anode block 13 or removed thereminal's by independent socket connections extending to from by virtue of the supporting structure now to be the respective metal block sections. described. A supporting block 30, preferably formed In this manner, filament or source can be readily disfrom stainless steel, is secured to the anode block 13 and mounted and a new source substituted with a considercarries a pair of combined support and terminal asable saving in the down time required for filament semblies 31 and 32. These assemblies include a pair or" changing in a mass spectrometer. It will be evident that threaded rods carrying, respectively, nuts 31a and 32a; the structure of the invention permits glass-to-metal seals sapphire bead insulators 31b, 32b, 31c, and 320; spacers to be eliminated, and permits the filament assembly to be 31d, 32d; connection lugs 31c, 32c; and gold plated put together Without requiring a jig operation. conical sockets 31 32 It will be evident that both Also, as will be evident from the foregoing discussion, sockets are insulated from the anode block by the in although the thermionic source of the invention is of sulator sets 31b, 32b, and 310, 320 while electrical conprincipal application in mass spectrometers, it is useful nection thereto can be made by the lugs 31c, 32c. generally in many varied types of thermionic emission Fitting within the lower socket 32 is a spherical condevices. tact member 33 secured to a threaded rod 34 carrying a Accordingly, it is an object to provide an improved sapphire bead insulator 35. The rod 34 is received within thermionic emission source which can be readily assema threaded opening in block it so as to make electrical bled and disassembled. connection therewith and, thence, passes through a larger it is a further object to provide such a source which opening in filament section 11, the protruding end havaccurately positions the filament without requiring a ing a nut 36 secured thereto which abuts a sapphire bead jig operation. insulator 37 fitting within an opening 33 in the filament it is a still further object to provide an improved mass lder Section 11- spectrometer emission source. In similar fashion, the upper socket Sly receives a It is a still further object to provide a filament assemsp ric l Conta t m m er 39 Which is ecured to a bly which is reliable i operation, rugged and ecgncmithreaded rod 40 carrying a sapphire ball insulator 41. cal. The rod 44} passes through a relatively large opening in Various other objects, advantages and features of the filament support section it) and is screwed within a tapped invention will become apparent from the following deopening 42 formed within the filament holder section 11. tail d description taken in conjunction with the accom- The filament Circuit therefore, be 'ifflcfid f panying drawings, in which: filament lead 44 through the lug 31c, socket 317, socket Figure l is a perspective View of an emission source 39, rod 49, filament holder section 11, filament l5, filaconstructed in accordance with the invention with the merit holder section 19, rod 34, socket 33, socket 32 parts in disassembled relation; and and lug 32a to a lead 45.

Figure 2 is a perspective view of the filament holder. When the filament holder is inserted into position with Referring now to the drawings in detail, I have shown the contacts 33 and 39 positioned Within the respective a filament holder having two metal sections 10 and ill sockets 32 and 31 a sapphire spacer ball 47 is snapped which are held apart by a plurality of sapphire ball into position within a slot 43 formed in the filament holder section 11. It will be noted that the sapphire ball 47 is urged into the slot by a spring 49 secured within a cup 50. This cup is threaded within a block 51 protruding from theanode support ,b1ock,13. Thus, the filament holder can be readily snapped into desired posi tion with relation to the anode block 13.

'in'one typical operation, ainumber of filament holders are utilized in a'succession of analyses, each holder having a filament secured theretoin the manner pre viously described. The samples to be analyzed are deposited on the respective filament ribbons in liquid form, and dried by passing current through the filament for a short time. A threaded rod, which can be inserted into a tapped opening 53, is attached to the filament holder to serve as a guide or handle, and the filament holder is brought up to its position next 'togthe anode block 13. The contacts 33 and 39' are placed into the sockets 32f and 31 the filament holder being rotated about the ball and socket contacts 33, 32] and 39, 31 toward the anode block 13 until the sapphire ball 47 seats in the slot 48. in this position, the ball clears the head of screw 15 and maintains the filament holder in desired fixed position relative to the anode block; The filament thereupon protrudes into the slot 22 exposing the sample to the to cause it to heat up so that'the analysis can be carried out.

When the analysis is completed, the current is turned ofi and the filament holder is removed simply by rotating or prying the assembly out from the anode block 13 until ball 47 snaps out of slot 48, releasing thejfilament holder. Ball 47 does'not fit so far into slot 48 that the spring must be released in order to remove-the holder. The sequence of removing the filament holder is exactly opposite of the installation sequence. Thus, the filament holder is readily removed and replaced by a new unit.

It will be evident that I have achieved the .obects' of the invention by providing a filament holder which can be rapidly inserted into position and'removedtherefrom.

When snapped into position, as described, the filament is supported in precisely the desired' position by the triangular support members 16, 17 and successive filaments are accurately positioned in' the location when new filament holders are inserted into the apparatus. Ithas'been found that there is substantially no variation in filament position when the present source structure is utilized, and that the time required to assemble the filament holder on the source unit is substantially decreased with resultant substantial decrease in pump down time.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and isnot intended to limit the invention.

7 I claim:

l.. A thermionic emission source forming a part of a thermionic emission device comprising, in combination,

7 an elongated block forming a part of said deviceyand a lament holder detachably secured to said block, said filament holder being formed from a pair of spaced insulated metal sections, a pair of elongated filament sup- I port members protruding from the respective sections and having guides at the outer ends thereof, a pair of pasformed at the apex of each triangular member, a pair of passages formed in said sections adjacent the edges of the respective triangular members, a filament carried by said members and received within said slots, the ends extending into the respective openings, means for detachably securing the respective ends of said filament within said openings, an elongated block, and means for detachably supporting said filament holder on said block and making electrical connections to the filament including, in combination, a pairofsockets secured to and insulated from said block, a rodsecured to one section of said filament holder and having a contact fixed thereto which seats in one of said sockets,.said rod being insulated from the other section, a second rod secured to said other section and insulated from said one section, the lastmentioned rod having a contact member secured thereto fitting within the'other socket, one of said sections having a slot formed therein, a snap element, and means urging said snap element into said last-mentioned slot to secure the filament holder in fixed position in respect to said block.

3. The structure of claim 2 wherein the sockets are of conicalconfiguration and the contact numbers are of spherical configuration.

4. A thermionic emission source which comprises, in combination, a filament holder having a pair of spaced metal block sections insulated from each other, atri angular member protruding from each block, a slot formed at the apex of each triangular member,-a pair of passages formed in said sections adjacent the edges of the respective triangular members, a filament carried by means for detachably securing the respective ends of said filament within said openings, an elongated block, and. 7

means for detachably supporting said filament holder on said elongated block and making electrical connections to the filament including, in combination, a pair of sockets secured to and insulated from said block, a rod secured a section, the lash-mentioned rod having a contact mem ber secured thereto fitting within the other socket, one of said sections having a slot formed therein, a snap element, and means urging said snap element into said lastmentioned' slot to secure the filament holder infixed position'in respect tolsaid block, said block having an elon-, gated passage'formed therein and said filament extending into said'passage'when the filament holder is assembled to the block, a pair of focus plates secured to the side of said block opposite said filament holder, and a plurality of sapphire balls spacing said focus plates from'the anode block.

5. A thermionic emission source which comprises, in combination, a filament holder having a pair of complementary metal sections spaced and insulated from each other, a filament detachably secured to the two sections,

an elongated-block, and means for detachably support ing said filament holder on said block and making electrical connections to the filament including, in combination,

, a pair of sockets secured to and insulated from said block,

a rod secured to one section of said filament holder and having a contact fixed thereto which seats in one of said sockets, said rod beinginsulated from the other section, a second rod secured to said other section and insulated from said one section, the last-mentioned rod having a contact member secured thereto fitting within the other socket, one of said 'sections'having a slot formed therein, a snap element, and means urging said snap elementinto said slot to secure the filament'holder in fixed position with respect to said block.

61A thermionic emission source which comprises, in combination, a' filament holder having a pair of spaced 5 metal block sections insulated from each other, a support member protruding from each block, a guide formed at the protruding end of each support member, a pair of passages formed in said sections adjacent the edges of the respective support members, a filament carried by said members and received within said guides, the ends of said filament extending into the respective openings, means for detachably securing the respective ends of said filament Within said openings, an elongated block, and means for detachably supporting said filament holder on said elongated block and making electrical connections to the filament including, in combination, a pair of sockets secured to and insulated from said block, a rod secured to one section of said filament holder and having a contact fixed thereto which seats in one of said sockets, 15 2,733,346

References Cited in the file of this patent UNITED STATES PATENTS 2,583,121 Raynolds Jan. 22, 1952 2,587,647 Pallette Mar. 4, 1952 2,703,843 Cameron Mar. 8, 1955 Oppenheimer Jan. 31, 1956 

